The Clinical Microbiology and Laboratory Core (Micro Core) in this application represents a fusion of the previously separate Microbiology Laboratory and Human Challenge Cores. The Micro Core will support specimen collection, transport, storage and testing for Dr. Cohen's studies in Project 1 and Dr. Elkins' studies in Project 2 including detection of gonorrhea, chlamydia and trichomonas in urogenital specimens and detection of genital ulcer pathogens with special emphasis on Haemophilus ducreyi from chancroid ulcers. Micro Core lab personnel perform commercially available, FDA-approved nucleic acid amplification detection assays and develop and validate in-house detection assays when no commercial product exists. A key role of the Micro Core will be to provide training and quality control and assurance plans for STD testing in Lilongwe, Malawi as required in Project 1. In addition, we will pursue an independent specific aim to characterize 1-1.ducreyi Class II strains in clinical specimens, founded on Dr. Elkins' recent discovery of an apparent second class of chancroid isolates detailed in the progress report for Project 2 in the current application. To examine the distributions of Class I and Class II H. ducreyi strains for this aim, we will collect and analyze clinical isolates from genital ulcers from geographically diverse populations including STD clinics in Malawi, Madagascar, Cameroon, Congo and China. We will characterize genotypic features associated with the two lineages by PCR amplification length polymorphisms and DNA sequence analyses of the dltA, dsrA and ncaA loci, and phenotypic traits by SDS PAGE and Western Blot for surface protein expression and antigenic characteristics, and in vitro antibiotic susceptibility testing. For Dr. Thomas' studies in Project 3, the Core will conduct human challenge experiments with Neisseria gonorrhoeae variants expressing combinations of pilE, pilC and recA mutations. The resources of the Micro Core include facilities in the UNC Department of Hospital Laboratories, the Verne S. Caviness General Clinical Research Center and in the Division of Infectious Diseases.